In this proposal we will characterize the expression of sprouty in renal development, murine development in general and in Wilm's tumors. We will characterize the mechanism of action of sprouty. Hence we will determine if sprouty is a growth inhibitor which may mediate some of the effects of WT1. We will determine at which steo in signaling through receptor tyrosine kinase sprouty acts. We then isolate partner proteins of spry which will lead to better idea of the molecular mechanism of sprouty. In order to determine the role of spry in normal and aberrant development we will determine in cell culture models and transgenic animals if engineered expression of spry interferes with normal renal morphogenesis. Finally to provide a critical role of sprouty as a target of WT1 important for renal development we will create knockout animals for sprouty one using conditiona cre-lox technology. Through these studies we will characterize an exciting molecule involved isgnal transduction and development. Spry may present a target for future strategies against Wilm's tumor, other malignancies and renal disorder such as polycystic kidney disease.